The goal of this pilot study is to determine the therapeutic efficacy and safety of the vitamin D analog 19-nor-1 alfa, 25 dihydroxyvitamin D2 for the treatment of plaque type psoriasis in adults. This will be accompanied by evaluating the topical application of either placebo petrolatum or petrolatum that contain 1.5 microgram of 19 -nor-1, 25(OH)2 in 0.1 g petrolatum. Expected outcome: only 19-nor-1, 25(OH)2D2 will be effective for treating psoriasis. This study plans to recruit 20 adults patients who have lesions over at least 5% of their bodies. Study subjects will be male or female between ages 18 & 80. The patient will apply to a 50cm2 lesion 0.10 g of white petrolatum that contains 1.5 mcg of 19-nor-1, 25(OH)2D2 once a day for 2 to 3 months. A comparable 50 cm2 psoriasis lesion will receive 15 mcg/g of white petrolatum daily. The study will be conducted in a double blind, right-left sided, self-controlled fashion. Neither the physician nor study nurse who is making assessment will know which lesion is receiving which compound.